Typically, in an offline download, a server of a downloader, instead of a client device, may download a file in response to a command from a user. If resources available for the file to be downloaded are scarce, the user may spend a long time to download the file via the client device, for example if download speed is low. By adopting the offline download, the server of the downloader is responsible for downloading the file, instead of the client device. In this case, the user may suspend, or shut down the downloader at the client device, thereby saving the time and electric charge. After the offline download is completed, the user may further download the file from the server of the downloader to the client device at a higher speed.
A typical offline download may include submitting, by a client, an offline download request. The offline download request may contain a download link address of a file. The download link address may be a Hyper Text Transfer Protocol (HTTP) link, an eMule link, a Bit torrent file, Magnet protocol link or any other download link address of the file. An offline task management server, upon receiving the offline download request submitted by the client, may send the offline download request to an offline task scheduling server. The offline task scheduling server may schedule an offline download server cluster, according to the offline download request, to perform the offline download. After the offline download is completed, the downloaded file may be stored in a cloud storage server, and the completion of the download may be reported to the offline task scheduling server. The offline task scheduling server may, in turn, inform the client to get the downloaded file from the cloud storage server. Bit Torrent (BT) is a content distribution protocol, which adopts a highly efficient software distribution system and peer-to-peer technology to share files, and is typically used in case of large files. BT also provides an upload service for the user. Further, BT may allow redistributing a download process across several nodes in the network. According to the Bit Torrent protocol, an issuer may create a .torrent file, i.e. BT torrent file as the file to be issued. The BT torrent file may contain references to one or more files that would be downloaded when a user selects the BT torrent file as a download target. The BT torrent file may also contain a download source for each file referred in the BT torrent file. The download sources may be the target from which the files in the BT torrent file need to be downloaded.
However, in a traditional offline download, if a user adds a BT torrent file for download, the server may download all files corresponding to the BT torrent file completely, which may extend the download time and may occupy substantial disk space.